The most common and most likely answer to this crossword clue is the 5 letter word LEHÁR
I've seen this crossword clue in The Guardian
L
E
H
R
More clues leading to the result LEHÁR
- Composer's husband entertained by tragic king
- Operettist Henry, creator of 20 covers
- Composer’s Shakespearean king eclipsing Henry
- Composer, tragic figure capturing hearts
- Composer‘s husband opens rogue parcel, non-PC
- Subtle harmonies more than sufficient for composer
- He composed some enjoyable harmonies
- Operetta composer: “Pardon one’s falling between two extremes”
- Composer drowned in Poole Harbour
- His music’s simple harmonies give away composer
Buddy explains!

The straight part
We know that "composer /composer" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case composer /composer = lehÁr.The cryptic/wordplay part
In cryptic crossword there's often an wordplay/cryptic part as well.This part involves a more complex hint, such as an anagram, homophone, hidden word, etc.
Sadly, We don't have an explanation for this specific crossword clue yet.